Hi there - I've recently upgraded my graphics card. My old card needed a couple of PCIe power cables - my new one doesn't. Can I just leave the cables plugged into the PSU but not the card? Or do I need to unplug them from the PSU? Caveat - I have no idea what I'm doing. Thanks for the help.

Some cards use 1,2 or even 3 I've seen PCIe power cable. If your card doesn't need them (and you have modular power supply whee you can remove the cable) then remove them to remove the mess of cables. If there is nothing plugged into them no power will be going thru them anyway.